Preheat oven to 350 and line a 8” square pan and an 9” round pan with parchment paper and spray with nonstick cooking spray.

Prepare cake batter according to package instructions and pour into prepared pans. Bake until a toothpick inserted into the middle of the cakes comes out clean, about 25 minutes. Let cakes cool completely.

Meanwhile, make the buttercream: In a large bowl using a hand mixer or the bowl of a stand mixer using the paddle attachment, beat butter until fluffy. Add powdered sugar and beat until combined, then add vanilla, heavy cream, and salt and beat until combined.

Place melted chocolate into piping bag or ziploc and snip off the ends. Draw a mouth, nose and eyes. Line the eyes with mini m&ms. Serve.

Lena AbrahamAssistant Food EditorLena Abraham is the assistant food editor at Delish.com, where she develops and shoots recipes for video and still photographs.

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